The present invention relates to a deflection apparatus that can be used with a horizontal deflection apparatus or a vertical deflection apparatus either of which uses groups of wound coils.
A cathode ray tube (CRT) for a computer monitor or a television set uses a horizontal deflection apparatus as a means for deflecting a picture into a horizontal position.
As illustrated in FIG. 1, the horizontal deflection apparatus has a saddle-shaped separator 10, inside of which groups of coils are wound separately into such saddle shape. Reference numeral 12 denotes the main structure of the separator which is made of resin and which has an upper bending portion 13 at its widest opening and a lower bending portion 14 at its narrowest opening. The horizontal deflecting coil groups 15 are wound separately around the upper bending portion 13 and the lower bending portion 14 in a predetermined area on the inside 12a (the side where the CRT is mounted) of the main structure of the separator 12, so as to be distributed in a predetermined manner.
FIG. 2 illustrates a typical example. The horizontal deflecting coil groups 15 are arranged in a position having a predetermined number of turns inside the main structure of the separator 12a, wound around hooks 16a to 16f of the upper bending portion 13 and partitions 17a to 17c in the middle of the main structure of the separator 12.
FIG. 3 is a schematic view illustrating the horizontal reflection apparatus 20 mounted on the CRT, which has an electron gun 22 in the neck 21a and the horizontal deflection apparatus 20 between the neck 21a and the funnel 21b. When receiving a sawtooth current, the horizontal deflection apparatus 20 scans and deflects an electron beam 23 horizontally onto a horizontal surface. Such deflecting apparatus is suggested in the U.S. patent application No. 832958 filed on Feb. 10, 1992 by this same applicant.
However, it is necessary to reduce the dissipation power because the screen of the CRT is enlarged and increases the horizontal deflection power. It is also necessary to reduce the horizontal deflection power in order to improve the picture quality and to reduce costs.
The horizontal deflection power PW is generally expressed in accordance with equation Eq.1. EQU PW=K.times.D.sup.2 .times.HV.times.Sin.sup.2 (0.5.times..theta.)/1(Eq1)
where K is the proportional constant, D is the diameter of the neck, HV is the CRT high voltage. .theta. is the deflection angle (FIG. 3), and 1 is the magnetic path length of the horizontal deflection apparatus 20 (FIG. 3).
It is also known that the horizontal deflection power PW can be determined in accordance with equation Eq2. EQU PW=L.times.I.sup.2 (mHA.sup.2) (Eq2)
where L is the inductance of the horizontal deflecting coil groups 15, and I is the deflection current.
From Eq1, it is possible to solve the problem of reducing to greatest extent possible the horizontal deflection power PW, by (1) reducing the CRT high voltage HV. (2) reducing the diameter of the neck (the CRT 21 and the separator 10), (3) reducing the deflection angle .theta., and/or (4) enlarging the magnetic path length l.
If the CRT high voltage HV is reduced, the luminance of the resulting picture is decreased because the speed at which the electron beam collides against the fluorescent screen 24 is decreased. If the diameter of the neck of the separator 10 and the CRT 21 is designed to be smaller, the diameter of the main electron lens in the electron gun 22 also becomes smaller, thereby causing the focus function and quality of the picture to deteriorate.
If the deflecting angle .theta. is reduced and the magnetic path length l is lengthened, the total length of the CRT 21 itself must also be lengthened and consequently the CRT becomes larger in size.
Thus, it is inappropriate to change the horizontal deflection power PW that is represented by the equation Eq1 because such change causes the picture quality to deteriorate and the CRT 21 to become longer.